The automated quantitative "Polybrene" technique for the study of red cell antigen-antibody reaction, developed in this laboratory, allows antibody detection on the order of one antibody molecule per red cell in the Rh system. Several modifications have been introduced which permit titration of cell-bound antibodies, direct determination of cell-bound antibody specificity, characterization of the thermal behavior of the reaction, and determination of immunological specificities based on inherent thermodynamic parameters. These techniques are being applied to the study of blood group systems and to antigen-antibody reactions associated with human autoimmune diseases. The work in progress has shown that by application of these techniques, laboratory profiles may be developed which establish clinical diagnosis and provide guidelines for patient management. The proposed investigation will achieve the following objectives: 1. By application of modifications of the Polybrene technique and additional immunochemical procedures, parameters will be developed for differentiation of various acquired hemolytic anemias according to etiology. The in vivo significance and clinical implications of each parameter will be evaluated. The data will be used to predict prognosis and select appropriate therapy. 2. Red cell antigens involved will be solubilized and their chemical nature will be determined. 3. The existing methodologies will be improved by the synthesis and use of more suitable Polybrene molecules, and by developing a manual test which will be applied to routine blood banking.